I have a G4 and a G5 in my T1 equipped office, both running 10.3.9
Each is capable of download speeds around 1100 kbps, on websites, or FTP downloads,
BUT upload speeds are excruciatingly slow at 22 kbps.
+ Transfers to and from local windows file server (via SMB) seem to be fine.
+ PCs on the same network have no problem uploading at speeds comparable to the download speeds.
+ an OS 9 machin on the same network has no problem uploading at speeds comparable to the download speeds.
I have switched my ethernet cable with those machines, and experience the same slowness.
Would be happy to provide additional inforamation to resolve this issue...